8800GT and windows 7 problem

once I install the nvidia drivers after the screen goes twice black and comes back on "detects the graphic cards" but first it takes too long then i get a message that says cant install try later. the cards are installed using windows 7 drivers but i need to enable sli and I cant see or get the control panel to install
however ntune can install and works fine. so

why nvidia control panel doesnt install on windows 7 64bit? is there a way to enable sli?

everything is freshly done, windows ect..sli bridge present, used to work fine with vista.